<template>
  <div class="popover" ref="popover">
    <div ref="contentWrapper" class="content-wrapper" v-if="visible" :class="{[`position-${position}`]:true}">
    <slot name="content" :close="close"></slot>
    </div>
    <span ref="triggerWrapper" style="display: inline-block">
      <slot></slot>
    </span>
  </div>
</template>

<script lang="ts">
  export default {
    name:"FreePopover",
    data () {
      return{
        visible: false,
      }
    },
    props:{
      position:{
        type: String,
        default: 'top',
        validator(value){
          return['top', 'bottom', 'left', 'right'].indexOf(value) >= 0
        }
      },
      trigger:{
        type:String,
        default: 'click',
        validator(value){
          return['click', 'hover'].indexOf(value) >= 0
        }
      }
    },
    mounted() {
      if (this.trigger === 'click'){
        this.$refs.popover.addEventListener('click', this.onClick)
      }else {
        this.$refs.popover.addEventListener('mouseenter', this.open)
        this.$refs.popover.addEventListener('mouseleave', this.close)
      }
    },
    destroyed() {
      if (this.trigger === 'click'){
        this.$refs.popover.removeEventListener('click', this.onClick)
      }else {
        this.$refs.popover.removeEventListener('mouseenter', this.open)
        this.$refs.popover.removeEventListener('mouseleave', this.close)
      }
    },
    computed:{
      openEvent(){
        if (this.trigger === 'click'){
          return 'click'
        } else {
          return 'mouseenter'
        }
      },
      closeEvent(){
        if (this.trigger === 'click'){
          return 'click'
        }else{
          return 'mouseleave'
        }
      }
    },
    methods:{
      positionContent(){
        const {contentWrapper, triggerWrapper} = this.$refs
        document.body.appendChild(contentWrapper)
        const {width, height, top, left} = triggerWrapper.getBoundingClientRect()
        const {height:height2} = contentWrapper.getBoundingClientRect()
        let positions = {
          top:{
            top:top + window.scrollY,
            left:left + window.scrollX
          },
          bottom:{
            top:top + height + window.scrollY,
            left:left + window.scrollX
          },
          left:{
            top:top + window.scrollY + (height - height2)/2,
            left:left + window.scrollX
          },
          right:{
            top:top + window.scrollY + (height - height2)/2,
            left:left + window.scrollX  + width
          },
        }
        contentWrapper.style.left = positions[this.position].left + 'px'
        contentWrapper.style.top = positions[this.position].top + 'px'
      },
      onClickDocument(e){
        if (this.$refs.popover && this.$refs.popover === e.target || this.$refs.popover.contains(e.target))
        { return; }
        if (this.$refs.contentWrapper && this.$refs.contentWrapper === e.target || this.$refs.contentWrapper.contains(e.target))
        {return}
        this.close()
      },
      open(){
        this.visible = true
        this.$nextTick(() => {
          this.positionContent()
          document.addEventListener('click', this.onClickDocument)
        })
      },
      close(){
        this.visible = false
        document.removeEventListener('click', this.onClickDocument);
      },
      onClick(event){
        if (this.$refs.triggerWrapper.contains(event.target)){
          if (this.visible === true){
            this.close()
          }else{
            this.open()
          }
        }
      }
    }
  }
</script>

<style lang= "scss" scoped>
$border-color: #333;
$border-radius: 4px;
  .popover{
    display: inline-block;
    vertical-align: top;
    position: relative;
  }
  .content-wrapper{
    position: absolute;
    border: 1px solid $border-color;
    border-radius: $border-radius;
    filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.5));
    background: white;
    padding: .5em 1em;
    max-width: 20em;
    word-break: break-all;
    &::before,&::after {
      content: '';
      display: block;
      border: 10px solid transparent;
      width: 0;
      height: 0;
      position: absolute;
    }
    &.position-top{
      transform: translateY(-100%);
      margin-top: -10px;
      &::before,&::after{
        left: 10px;
      }
      &::before{
        border-top-color: black;
        border-bottom: none;
        top: 100%;
      }
      &::after{
        border-top-color: white;
        top: calc(100% - 1px);
      }
    }
    &.position-bottom{
      margin-top: 10px;
      &::before,&::after{
        left: 10px;
      }
      &::before{
        border-bottom-color: black;
        border-top: none;
        bottom: 100%;
      }
      &::after{
        border-bottom-color: white;
        bottom: calc(100% - 1px);
      }
    }
    &.position-left{
      transform: translateX(-100%);
      margin-left: -10px;
      &::before,&::after{
        transform: translateY(-50%);
        top: 50%;
      }
      &::before{
        border-left-color: black;
        border-right: none;
        left: 100%;
      }
      &::after{
        border-left-color: white;
        left: calc(100% - 1px);
      }
    }
    &.position-right{
      margin-left: 10px;
      &::before,&::after{
        transform: translateY(-50%);
        top: 50%;
      }
      &::before{
        border-right-color: black;
        border-left: none;
        right: 100%;
      }
      &::after{
        border-right-color: white;
        right: calc(100% - 1px);
      }
    }
  }
</style>